UPDATE:  Pressure tested it and it's all good.  Installed that "restrictor" I mentioned that's basically just a 1" hole.  It's really cool now- like 160-170 in the thermostat housing.  Also replaced the sending unit in the head and that's showing me around 130-140.  Shooting down the center of the oil filler tube with a temp gun is now about 125 where it was 200 before.  

I DO think the old sending unit was bad.  I also tested the Moon sight gauge (mounted at the thermostat housing) against my meat thermometer and a new in box Stewart Warner mechanical temp gauge and the Moon gauge was the most accurate of the 3- I know this because it was the only one reading close to 212 when the water in the pot on my stove began to boil.  

I picked up that NAPA high flow thermostat today and have it just in case.  

Thanks again.  

I wanted to give another update and thank everyone here.  (Knock on wood) it seems fine.  I put in the NAPA #6 high flow thermostat and that seems to have made all the difference...that and having a known good temp sender.  It's staying right around 160 in the head and between 190-200 in the thermostat housing.  Ran into an issue with the housing leaking (again) but I cinched it down and it MAY be fine.  

It seemed like it was fine yesterday running around but there was a drip hanging on the bottom of the thermostat housing after it had sat parked for a few hours.  I got to wondering why a 16# cap was necessary so I put a 7# cap on.  Maybe less pressure on that joint, or maybe this blind squirrel found a nut.  

Thanks again to all.